Regulating mechanism



Nov. 29, 1932. 0. N. BRYANT 1,889,535

REGULATING MECHANISM Filed Dec. 30, 1930 INVENTOR 0220 N. BQYANT.

BY .3..M

ATTORNEY Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE OZRO N. BRYANT, OF MOORES, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA REGULATING MECHANISM Application filed December 30, 1930.

My invention relates to a regulating mechanism, for example a fluid pressure regulator, and it has for its object to provide a regulating mechanism having improved operation.

Pressure regulators as heretofore constructed are adapted to maintain a fluid pressure within limits. Variation of pressure within said limits is required to provide the proper position of the valve means.

It is a more particular object of my invention to provide a fluid pressure regulating mechanism which restores the fluid pressure to a predetermined value.

In accordance with my invention, I provide a pressure-responsive element and a weight member which opposes the force of the fluid pressure and balances the predetermined value of said fluid pressure. Movement of the weight member is retarded by suitable means, and the weight member is connected to the pressure-responsive element through a spring, so that upon variation in pressure, the spring permits an immediate initial movement, the extent of which is determined by the scale of the spring. The

weight member then moves at a retarded rate, due to the change in deflection of the spring, to continue movement of the pressureresponsive element until the predetermined value of pressure is restored.

The above and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing forming a part of this application, in which:

The single figure is a diagrammatic view showing the regulating mechanism applied to a non-condensing or back pressure turbine driving an electric generator.

Referring to the drawing more in detail, 10 indicates a non-condensing or back pres sure turbine, which partially expands high pressure motive fluid and discharges the same at a desired pressure to an exhaust conduit 11. The back pressure turbine serves not only the purpose of a pressure-reducing valve, but also the further purpose of utilizing the energy made available by the drop in pressure to develop power.

The exhaust fluid is conveyed through the Serial No. 505,608.

conduit 11 to any apparatus in which such fluid may be used, for example heating apparatus, as is well-known in the art. The turbine 10 drives a synchronous generator 12 which is connected to an alternating current power line 13. A turbine generator 12 is also connected to the power line 13 and de termines the frequency of the alternating current in the power line. As is well understood in the art, the generator 12 is maintained in synchronism with said frequency. This means that the quantity of motive fluid flowing through the turbine 10 may be varied without affecting the speed of the turbine and generator, the speed being maintained substantially constant by the connection with the power line.

The turbine 10 is provided with an admission valve 14 controlled by a governor 15, the latter including an operating piston 16 connected to the valve 141 by a fulcrumed lever 17. The piston 16 operates in a cylinder 18 and is biased downwardly in valve-opening direction by a spring 19. Fluid pressure varying as the square of the speed of the turbine is developed by an impeller pump 21 and admitted to the lower portion of the cylinder 18 to bias the piston 16 in valve-closing direction. A restricted flow of fluid underpressure into the upper portion of the cylinder 18 is provided by an orifice 22, which may be formed in the piston 16.

The pressure of the fluid in the upper portion of the cylinder 18 is controlled by a regulating mechanism indicated generally by the numeral 23. The latter includes a pressure relief valve 24 communicating with the upper portion of the cylinder through a conduit 25. The valve 24 controls the escape of fluid from said upper portion and, therefore, controls the pressure therein. The valve 2 1 is biased to closed position by a compression spring 26, interposed between the valve and an operating piston 27 of a fluid pressure relay.

The piston 27 operates in a cylinder 31 and is formed with a central opening through which a stem 28, constituting the pilot valve of the relay, is extended. The stem 28 is formed with a slot 29 in the lower portion a conduit 38.

, weight elements extending through the piston. A restricted flow of fluid under pressure is admitted to the upper portion of the cylinder 31, said fluid under pressure being preferably provided by the pump 21 and conveyed through a conduit 32; an orifice 33 being provided in the conduit to restrict the flow. A drain conduit 30 communicates with the lower portion of the cylinder 31. V

The pilot valve stem 28 is connected to a lever 34, which bears upwardly against a knife edge fulcrum 35. A stem 36 connected to a pressure-responsive diaphragm 37, bears upwardly against the lever 34. The diaphragm 37 is subjected on its lower side to the pressure of the fluid in "the exhaust conduit 11, said pressure being conveyed through A slight spring 36 may be provided to support the weight of the stem. As themovement of the stem 36 is slight, the scale effect of the spring 36' will be negligible. This spring may be omitted if desired.

The lever 34 is biased downwardly by a weight member 39, which comprises a carrier member 41 suspended from the lever through a tension spring 42, and a group of 40 carried on the carrier member. The total weight of the weight member 39 is such. that, together with the weight of the lever 34 and the other parts carried thereby, it will just balance the force of the fluid pressure transmitted by the stem 36 when said pressure is at the predetermined value which it is desired to maintain. By adding or removing weight elements, the predetermined value of the fluid pressure maintained by the regulating mechanism may be varied. A dash pot 43 is provided for r tarding the rate of movement of the weight member 39, and includes dash pot piston 44 disposed in a cylinder 51 with relatively large clearance. The piston 44 is connected to the carrier member through stem The stem 45 has a portion 46 of reduced diameter extending through a central opening 50 in the piston 44, and a shoulder 47 formed on the stem 4o constitutes a valve to control the flow of fluid through the opening terposed between a p 49 on the lower end of the stem 45 and the piston 44, biases the piston upwardly against the shoulder 47, tending to close the opening 50. Upon upward movement, the spring 49 permits the piston 44 to lag slightly, uncovering the opening 50 and permitting flow of liquid therethrough. The dash pot, therefore, permits a slightly greater rate of movement in upward direction.

The operation of the above-described apparatus is as follows: Since the speed of the turbine is maintained substantially constant by reason of connection of the generator with the power line 13 as above-described, the pressure beneath the piston 16 will be substantially constant, so that the admission of motive fluid to the turbine in normal operation will be regulated almost entirely by the regulating mechanism 23 in response to em haust pressure. Assuming a decrease in demand for exhaust fluid conveyed through the conduit 11, the pressure thereof begins to increase. The increased pressure is imposed on the diaphragm 3"? and conveyed through the stem 36 to the lever 34. The increased upward bias on the lever 34 moves the same upwardly and increases the tension of the spring 42, the weight member 39 being momentarily held substantially stationary by the dash pct 43. The increase in defection of the spring 452 and the upward movement of the lever 34 proportional to the increase in fluid'pr'essure.

Upon upward movement of the pilot valve stem 28 with the lever 34, a greater portion of the slot 29 is uncovered by the piston 27, thereby discharging fluid from the upper portion of the cylinder 31 at a greater rate than that which it is admitted. The operating piston 27 is moved upwardly, therefore, by the comprsion spring until the slot 29 again provides a discharge opening permitting a rate of discharge eo, Lal to the rate of admission. The decreased compression of the spring 26 decreases the'setting of the pressure relief valve 24.

The pressure relief valve 24 thereupon decreases the pressure in'the upper portion of the cylinder 18, anl the'piston 26 ismoved upwardly in valve-closing direction. The admission valve 14 restricts the admission of motive to the turbine 10.

The movement just described is the initial movement which is instituted immediatey upon a change in pressure of the exhaust fluid and serves to restrict further change in pressure.

In order to restore the pressure to the predetermined value, the following movement continuous at a retarded rate. The increased tension of the spring 42 exerts a greater upward force on the weight member than the weight of .the weight member, so that said weight member moves upwardly at a rate permitted by the dash pot 43. The lever 34, therefore, continues to move upwardly at a retarded rate. Said upward movement causes the admission valve 14 to be moved slowly in valve-closin g direction, in the man ner just described.

As the supply of motive fluid is further restricted, the pressure begins to decrease, and when it has decreased to the predetei-- mined value, the tension of the spring will have been reduced to that effected by the weight of the weight member 39. The mechanism is then in equilibrium and will remain stationary until a subsequent change in eX- haust pressure occurs.

Assuming an increase in demand, the pres-- sure of the exhaust fluid decreases. The upward bias transmitted through the stem 36 to the lever 34 decreases below that necessary to balance the force which the tension spring 42 is exerting on the lever 34. The spring 42, therefore, moves the lever 34 downwardly until it again balances the force of the fluid pressure, the weight member 39 being again held substantially stationary for the moment by the dash pot 43. Upon downward movement of the pilot valve stem 28 with the lever 34, the discharge of fluid from the upper por tion of the cylinder 31 is cut ofl, thereby increasing the pressure of the fluid therein. Said fluid pressure moves the operating piston 27 downwardly until the slot 29 is again uncovered to provide suflicient discharge opening. The increased compression of the spring 26 imposes increased closing force on the pressure-responsive valve 24, and the latter increases the pressure in the upper portion of the cylinder 18. The piston 16 thereupon moves the admission valve 14 in open ing direction to provide increased admission of motive fluid to supply the increased demand for exhaust fluid.

The movement just described is also an initial movement which takes place immediately and which is followed by a further movement at a retarded rate. The force 01 the spring 42 is now insuflicient to support the weight of the carrier member 41, and the latter begins slowly to move downwardly, its rate being again retarded by the dash pot 43. The central opening 50 in the dash pot 44, in this instance, is closed by the shoulder 47, to provide maximum retarding effect in this direction. The lever 34 is slowly moved downwardly to effect further opening movement of the admission valve 14 to restore the predetermined pressure.

As the pressure in the exhaust conduit 11 begins to increase and return to the predetermined pressure, the deflection of the spring 42 slowly increases. As the pressure attains the predetermined value, the spring 42 attains the deflection at which it just balances the weight of the weight member 39, thereby discontinuing further movement of the regulating mechanisn It is to be noted that the variable force required to compress the spring 26 is provided by the relay and not by the lever 34, the latter merely actuating the pilot valve of the relay. There is, therefore, no scale effect imposed on the lever 34.

For the purpose of the appended claims, the lever may be considered as the pressureresponsive element, the variable force of the fluid pressure being transmitted thereto.

From the above description, it will be seen that I have provided a novel construction of regulating mechanism which effects an immediate movement to restrict change in the fluid pressure or other operating condition in response to which it acts, and which then continues at a retarded rate to operate until the predetermined pressure or other value is restored.

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications Without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposec by the prior art or as are specifically set forth in the appended claims.

IVhat I claimed is:

1. The combination with apparatus to be regulated, of mechanism for regulating said apparatus in response to a variable operating condition thereof comprising a movable element, means for biasing said element with a force varying with the operating condition, a weight member for biasing the movable element in opposition to said force, a spring for connecting the weight member to the movable element and serving upon variation in said force to provide a temporary scale for the movable element to determine the extent of initial movement thereof, means for retarding the rate of movement of the weight member, a fluid pressure relay controlled by the position of the movable element, and means controlled by said relay for effecting the regulation of said apparatus.

2. In a fluid-pressure regulating mechanism, the combination of a pressure-responsive means biased by the fluid pressure to be regulated, a weight member opposing the bias of said fluid pressure on the pressure-responsive means, dash pot means for retarding the rate of movement of the weight member, a spring connecting the weight member to the pressure-responsive means and serving upon variation in fluid pressure to provide a temporary scale for the pressure-responsive element to determine the extent of initial movement thereof, a relay controlled by the position of the pressure-responsive element, and valve means controlled by said relay for controlling the flow of fluid to maintain the fluid pressure.

3. A fluid-pressure regulating mechanism operating upon variation in pressure to restore a predetermined value thereof compris ing the combination of pressure responsive means including a movable element subjected to the variable force of the fluid pressure to be regulated, a weight member whose weight balances the unbalanced force of said fluid pressure on the movable element, means for retarding the rate of movement of the weight member, a spring for transmitting the weight of the weight member to the movable element and providing a temporary scale to determine the extent of initial movement of the movable element upon variation in fluid pressure, a relay controlled by the position of the movable element, and valve means controlled by said relay for controlling the flow of fluid to maintain said fluid pressure.

4. The combination *ith a prime mover, of means for regulating the flow of fluid through a stage of the prime mover so as to maintain a constant pressure at some point in the path of the fluid comprising a pressure-responsive means subjected to the pressure of the fluid at said point, a weight member connected to said pressure-responsive means so that its weight opposes the force of the fluid pressure on the pressure-responsive means, the connection in cluding a spring which provides a temporary scale for the pressure-responsive means, a dash pot for retarding the rate of movement of the weight member, a fluid pressure relay controlled by the position of the pressure-responsive means, and means controlled by the relay for regulating the flow of fluid through said stage.

5. The combination with a prime mover having an admission valve, of regulating mechanism therefor comprising a pressureresponsive element subjected to the pressure of motive fluid flowing through the prime mover, movable weight means for opposing the bias of the fluid pressure on element, means for transmitting the bias of the weight means to said element and including a spring through which the bias is transmitted, dashpot means for retarding the rate of movement of the weight means, a fluid pressure relay including a pilot valve movable by the pressure-responsive element and an operating piston, and means responsive to the position of the operating piston for regulating the admission of motive fluid to the prime mover.

6. The combination with apparatus to be regulated, of mechanism for regulating said apparatus in response to a variable operating condition thereof comprising a movable element, means for biasing said element with a force varying with the operating condition, a weight member for biasing the movable element in opposition to said force, a spring for connecting the weight member to the movable element and serving upon variation in said force to provide a temporary scale for the movable element to determine the extent of initial movement thereof, means for retarding the rate of movement of the weight member, and means controlled by the posi tion of said movable element regulation of said apparatus, tioned means including a controlling element actuated by the movable element and means for applying power under control of said controlling element to eli ect the regulation 7. In a regulating mechanism eflecting a regulating action in response to a variable force, the combination of a movable element subjected to the variable force, means for biasing the movable element, a spring interposed between the biasing means and the for effecting the said last-menmovable element, means for retarding the rate of movement of the biasing means, and a fluid pressure relay controlled by the position of the movable element and effecting the regulating action, whereby, upon change in the variable, force, the deflection of the spring is varied to provide an initial movement of the movable element, and the biasing means moves at a retarded rate to provide continued movement of the movable element.

8. In a regulating mechanism eflecting a regulating action in response to a variable force, the combination of a movable element subjected to the variable force, means for biasing the movable element in opposition to the variable force, a spring interposed be tween the biasing means and the movable element, means for retarding the rate of movement of the biasing means, and a fluid pressure relay controlled by the position of the movable element and effecting the regulating action, whereby, upon change in the variable force, the deflection of the spring is varied to provide an initial movement of the movable elerbiasing means moves at led rate to provide continued moveent, and the a reta ment of the movable element.

i 1 testimony whereof, I have hereunto subscribed my name this 19th day of Dec, 1930.

OZRO N. BRYANT. 

